Discrete Outputs; Switches / Discrete Inputs - Garmin GNS 480 Installation Manaul

2.8.8

Discrete Outputs

2.8.8.1 ILS Energize
P7-33 ILS Energize
The ILS Energize output is grounded whenever a localizer frequency is tuned on the GNS 480 nav radio,
regardless of which navigation source (GPS or VOR/ILS ) is currently selected to drive the CDI.
2.8.8.2 Precision Approach
P5-68 Precision Appr
The Precision Appr output is grounded when a precision approach is active. The GNS 480 shall set the
output active when either: 1) the CDI is set to the NAV radio and a localizer is tuned as the active NAV
frequency; or 2) the CDI is set to GPS, a GPS approach with vertical guidance is loaded, and the aircraft is
within 31 NM of the landing threshold point of the destination runway. This output may be connected to
the ILS Energize input of an autopilot or flight director to provide higher autopilot gain when the GNS
480 is operating in precision approach mode.
2.8.8.3 Audio Message Active Out
P5-70 Audio Msg Active Out
The Audio Msg Active Out is grounded whenever the GNS 480 is playing an audio message or audio
tone. This output is grounded 200 msec prior to playing the message / tone, and remains grounded for 200
msec following completion of the message / tone.
2.8.8.4 Power Control Out
P7-36 Power Control Out
The Power Control Out is grounded whenever power is applied to the GNS 480, and open otherwise.
2.8.8.5 Discrete In / Out
P5-72 Discrete In/Out 1
P5-73 Discrete In/Out 2
P5-74 Discrete In/Out 3
P5-75 Discrete In/Out 4
The four Discrete In/Outs are software-configurable as inputs or outputs. These are general purpose
inputs/outputs whose function depends upon what interfaces are configured on the GNS 480.
2.8.9

Switches / Discrete Inputs

Installations in conformance with the requirements specified in this installation manual do
not require the use of any external switches, since all switches are provided on the GNS
480 front panel.
All of the switch inputs duplicate functions available on the front of the GNS 480. These can be used to
make the function available remotely.
2.8.9.1 CDI Select Switch
P7-8 Main CDI Select In
The Main CDI Select In is used to toggle between the display of GPS and VOR/ILS information on the
CDI window and remote CDI connected to the Main CDI outputs. A momentary ground on this input
performs the same function as pressing the CDI key on the GNS 480 bezel.
GNS 480 (CNX80) Installation Manual
NOTE
560-0982-01 Rev L
Installation Procedures
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